DE2628709A1 - TV and telephone link for documents - permits transmission of images and marking joints by light pen with compensation for transit time delay - Google Patents

Abstract

A TV/telephone link permitting the display of documents superimposed on the transmitted images of the two subscribers. Two subscribers (A, B) are connected through an exchange (w); each has a normal telephone instrument (F1, F2), a camera (K1, K2) and a picture display unit (B1, B2). The camera (K1) receives directly the image of the subscriber, and through a mirror the imate of a document to be transmitted, which it converts to a signal to be transmitted to the other subscribers display unit (B2), and vice versa. The receiving subscriber is provided with a light pen (L) so that a specific point on the displayed image can be identified and marked on both display units (B1, B2). Removal of the light pen from its holder activates a number of contacts to activate a pulse transmission circuit which assures compensation for the transit time between subscribers to that the spot displayed to the first (sending) subscriber is identical with that marked on the screen by the receiving subscriber.

Description

Procedure for a television telephone system for joint

Seeking an image by two participants The invention relates to a method for a television telephone system in which to view a Image by two participants from the sending point the image, e.g. a drawing, transmitted via the one image channel to the image display device of the receiving station is, at the receiving point with the help of a coordinate input device, such as E.g. a non-stylus, a trackball or a joystick, one on the Screen of both bodies to be made visible, being at the receiving end Contacts actuated during commissioning of the electrical data input device are used to activate this coordinate input device, to connect the two Bila channels to the necessary devices, and to disconnect the recording camera the receiving agency.

Because of the finite transmission distance between two subscriber stations all signals and pulses are subject to a delay time shift, their size is essentially dependent on the cable length. This delay in running time causes that the co-ordinates of the visible character, which is sent by the body receiving the image, with which a certain point is marked on the transferred template, at a completely different point appears on the self-image (control image) of the sending body.

In order to avoid this delay in running time, it is from the DU-AS 2 017 024 known to transmit the image from the sending to the receiving point, there, in the right place, to mix the visible sign with the image signal and transmit the television signal thus obtained back to the transmitting station, where it is displayed is displayed on the screen exactly as it is at the receiving station. on in this way the image signal traverses the route twice, so that the maximum distance must be halved between two participants if an image is of the same quality should be visible on the screen of the sending entity.

The object of the invention is to provide image transmission between two television telephone subscribers make such that the maximum distance between the two participants does not need to be reduced, even if there is a visible mark on the screens the participant is to be shown.

This is achieved according to the invention in that at the receiving Set the synchronization signals from the incoming image signal in an isolator be separated that at this point from the commissioning of the Xoordinateneinabgerätes an impulse for the forced switch to in this with every picture change Self-image is generated by the sending participant that the synchronization signals Eigenbildumschaltungimpulse and those determined by the coordinate input device Coordinates of the visible character corresponding impulses added in a mixer stage and transmitted to the sending station via the associated image channel that the Self-image switching impulse in addition to switching to self-image at the sending one Place is detected by a detector and causes the time interval of the synchronization signals received from the sent with the help of at least one Measure the counter and at least one clock generator incrementing this counter, whereupon the counter is stopped and waits for a coordinate pulse to return it switches on that in the case of missing the coordinate pulse the counter at next synchronization pulse is reset and starts counting again, that if a coordinate pulse has switched on the counter, it continues to count, until a specified, technical data (picture standard) of the television telephone system The corresponding number has been reached, and that when this number is reached the visible Character is displayed in the image signal to be transmitted.

From D-AS 2 017 024 it is also already known, a synchronization signal by separating the received image information from the signal. The light pen marking the point of interest is sent to the Bred desired position in the grid of the received image, creating a position indicator signal is generated, which by means of superposition with the separate synchronization signal is sent back to the sending station, a computer. That produced in this way The position indication signal superimposed on the synchronization signal becomes after reception in the transmitting station again separated from the synchronization signal. The synchronization signal becomes further into the horizontal sync signal and the vertical sync signal in this case divided up. These synchronization signals are then used to open corresponding Gate members, so that these pass pulses generated by oscillators.

The impulses let through by the gate sections are transmitted to a horizontal or vertical pulse counter applied. By locking these gate sections, the counters stopped again. In this way, the position indicator signal becomes unambiguous digitized horizontal and vertical signals converted to those of the horizontal and vertical position of the point designated in the receiving station. These digit signals are processed directly by the computer. Such a thing Sending back a positioning designation signal from a television telephone subscriber to a second television telephone subscriber is not provided in this form, but in the manner described above, with the image signal twice the entire route must go through between the two participants.

The invention has the advantage that even in traffic between two television telephone subscribers the picture is only transmitted in one direction, so that the full range is used as the distance between the two participants can be.

By the fact that the Rigenbildumschaltungimpuls from the receiving station are transmitted to the sending body, it is not only ensured that on the Screen of the sending body the sent image with the displayed visible Sign can be seen. With these impulses the devices are switched on, those for receiving the coordinates of the visible character and for their correct positioning are required in the sent image, such as isolating circuits, generators, Counter etc.

or at least one detector, which then receives the incoming signals under3urhts whether they come from a normal television telephone or the positioning information of a marked point.

An example of the invention is described in more detail with reference to the drawing. While in Fig.1 the devices are shown that are necessary for understanding the invention and all the other details found in a standard television telephone system are required anyway, have been omitted, the classification of the individual is shown in FIG Pulses shown in the sync signals.

In Figure 1, W represents the telecommunications switch, with the help of the two Participants A and 3 are connected to one another by many others. Both participants So have Bernsehtelefon terminals, each consisting of a telephone 21 or F2, a television camera xl or K2 and an image display device B1 or B2 exist.

The two telephones F1 and F2 are on a line c and the Mediation W connected to each other in a known manner and are used to establish the connection build up and transmit the voice frequencies between the two participants.

During a normal television phone connection, the camera Xi a picture of the participant or, via a mirror, the picture of a document, a Document or a drawing recorded and via the one image channel a to Image reproduction device B2 of interlocutor B transmitted. In the opposite direction the image recorded by the camera K2 reaches the image channel b to the image display device 31 at subscriber A. All necessary for this transmission Devices are known, so their description is not included here.

For the following consideration, subscriber A should provide an image N. transferred to subscriber B, both subscribers should be forced to do so the bilichannels must be switched on so that they can only see picture N on their picture display devices see, and the participant B is to use a coordinate input device, for example a light pen L to mark a certain point P on his screen, so that this point can also be seen on both image display devices B1 and B2. The visible character P can, depending on the design of the coordinate input device, a white spot, a black spot, a blinking sign, an alternating one white and black points or a character with a striped pattern. The invention is not affected by the nature of the mark.

The same facilities are located at subscriber station A, as with the subscriber station B, and vice versa, so that either the subscriber station A or the subscriber station B can be the sending station within the meaning of the invention. Switching is carried out, for example, by the sending subscriber his light pen L puts in an appropriate holder, so that the participant A can remove its light pen from the holder. This will make some contacts which switch the required transmitting and receiving devices accordingly.

Since television telephone subscribers A and B are apart, Every character transmitted needs a certain amount of time, the runtime after which it is other participant arrives. When transmitting images with high sampling frequencies works, this is noticeable in that the visible sign, the .der Subscriber B marked on his screen B2, at subscriber A to another Time arrives, and is therefore in a completely different place. With help the circuit arrangement according to Fig.1 becomes the visible character P transmitted via the image channel b to subscriber A and there in such a way in that of the Camera Ki recorded image, the one with blanking interval, sync pulses, etc. to the BAS signal is added, inserted at the right moment, so that it is both at the participant A on his screen B1 via the self-image contact 4 as well as on the screen 32 appears.

At the beginning of the image transmission, participant A sets up his camera K1 to the image N to be transferred. In the units not shown here, the image is added to the BAS signal and transmitted to subscriber B via the image channel a. There it appears on the image display device 32. Now participant B wants to Mark point P, so he takes the light pen t out of the holder and operates it thus a number of contacts. One of these contacts ensures that the contact 2 is opened and contact 3 at subscriber B is closed. This is the Camera K2 separated and the separator S and the coordinate input device E over a mixer M2 connected to the image channel leading to subscriber A. That Coordinate input device then sends a self-image switching pulse e (Fig. 2) to the terminal of subscriber A. This pulse is picked up by the detector U, the by opening the contact 4, the image display device 31 is independent of self-image from other contacts, manually operated by this participant, on self-image switches. In addition, the contact 1 is closed and located between the detector U and this contact 1 are activated. This self-image switching impulse e is transmitted with each image until the light pen L returns to its holder.

Each subscriber station is equipped with an S or R separator. This device is used to separate the synchronization signals from the incoming image signal BAS. In this case it is assumed that the vertical sync pulses v and the Horizontal sync pulses h serve as synchronization signals, in each case the leading edge of these impulses.

If now participant B touches the tip of his light pen B to the Presses point P of his screen B2, the coordinate input device E in known Way determines in which line and at which point (point) within the line the point P is located. The electron beam of the image display device B2 has a Needed a certain amount of time to sweep over several lines since the vertical blanking interval v to reach point P. This time interval now serves as a criterion on which Place the point P as a visible symbol in the image signal to be transmitted is. For this purpose, the synchronization signals v and in the mixer ME h, the self-image switching pulses e and those corresponding to the coordinates of the point P. Pulses d (Fig. 2) are added and transmitted to the sending point A via the image channel b. The synchronization signals normally generated by the camera unit at subscriber B K2 are not required and are therefore kept away from image channel b.

The detector U at the subscriber A now represents the presence of a or several of these impulses in each image and conducts them after activation of the required devices to the racing link R, where they are separated from each other. In which The manner in which the self-image switching pulses e are used has already been described.

Corresponding to the two types of synchronization signal, namely the vertical synchronization signal v and the horizontal sync signal h, the separator R has two outputs, over which the respective synenronization impulses are conducted. This is how the vertical sync pulse arrives to a sequential control Jl and the horizontal sync pulse to a sequential control J2. These two sequential controls also have inputs from those not shown here Devices that set the following counters in the correct Rethen order start and stop.

After the self-image switching impulse e arrives at participant A the outgoing vertical sync pulse starts the counter Zl, which is from the clock generator Tl is advanced. This verti- cal sync pulse is in the subscriber station B to define the marking point P further processed and thus reaches the sending subscriber again with a delay via the return channel b A, where the leading edge from the separating circuit R over the sequential control J1 the counter Zl stops and the runtime-related delay in the vertical direction is therefore fixed Only when the coordinate pulse d arrives does the counter Z1 start again and continues to count until the set number, which is based on the technical data of the TV telephone system (picture standard) is dependent, is achieved. Then the counter gives Zi a pulse to the gate G and the subsequent pulse shaper IF for insertion into the self-image via the mixer stage Ml.

The horizontal sync pulses are generated by the sequential control system in an analogous manner J2, the counter Z2 and the clock generator T2, with the difference that the Counter Z1 counts in a line cycle, while the clock generator T2 counts clock pulses in time The distance between two pixels must generate within a line and the counter Z2 thus from the beginning of the line, the number of pixels counts in each pixel spacing.

In principle it would also be possible to have just one meter, one To use a clock and a sequencer. The clock would then have to be in the speed of the clock 2 count, so that a correspondingly large counter Z should be provided.

As soon as one pulse each from the counter Z1 and from the counter Z2 at the same time is applied to the AND gate G, this gate is switched through and that already described visible characters in the image signal to be transmitted in the mixer Ml displayed.

The chronological sequence of the individual signals is shown in FIG shown. As already described, the time segment v represents the vertical sync pulses and the signals h represent the horizontal sync pulses. The self-image switching pulse In this drawing, e is placed on the first blank line. This pulse but can also, depending on the television telephony system used, within the vertical blanking interval, placed in one of the blank lines or transmitted together with the image signal.

This does not affect the invention in any way.

According to this example, the coordinate pulse d should be approximately in in the center of the picture.

The upper curve of Fig.2 shows the transmitted BAS signal, which as an information image from the sending subscriber A via the image channel a to the receiving party Participant B arrives. In the lower curve is the one arriving at the sending subscriber A. Return signal shown, the coordinate pulse d and also the Eigenbildumschalteimpuls e contains.

The transit time of the signals from the sending to the receiving and back to the sending point A the time f, the distance of the coordinate impulse is d from the reference edge of the vertical sync pulse v is the time x.

A numerical example should illustrate the momentum ratios even better. It is assumed that for interlaced transmission of a field 128 lines can be formed.

The counter Zl is then constructed in such a way that it counts up to 128. With the beginning The counter Zl is started de s of the vertical sync pulse v in the upper curve and stopped again at the beginning of the vertical sync pulse v in the lower curve. The counter has a running time of f, for example the duration of 35 lines, established. At a distance from x, i.e. when the coordinate pulse d occurs, Another period of 50 lines has elapsed. Since the count began So so far 85 lines have been transferred. The counter will now start again and it counts, starting with 36, up to the number 128; so he still has 93 steps to go do. When the number 128 is reached, it sends an impulse to gate G to Fading in of the visible character P. Since by then the time of 178 lines had passed the visible character is displayed in the 50th line of the next field, so that the required distance x is maintained.

As in Fig. 2, the definition of the line for the visible Character P has been described, the distance of the coordinate pulse is also in the same way measured from the previous horizontal sync pulse h. The coincidence of the two Impulse at gate G results in the exact fade-in pulse into that of the sending one Position A, visible characters P to be displayed.

2 claims 2 figures

Claims (2)

P a t e n t a n s p r ü c h e 1. / Procedure for an amber telephone system, in the for joint viewing of a picture by two participants of the sending Put the picture, e.g. a drawing, over the bila channel to the picture display device the receiving point is transmitted at the receiving point with the help of a Coordinate input device, such as a light pen, a trackball or a Joystick, a sign visible on the screen is placed that indicates the TV signal is mixed in a mixer to simultaneously on the Screen of both bodies to be made visible, being at the receiving end Place when the coordinate input device is put into operation, contacts are actuated are used to activate this coordinate input device, to connect the two Image channels to the required devices, and to disconnect the recording camera the receiving body, that is not indicated at the receiving end Place (B) the synchronizing signals from the incoming image signal (BAS) in a separator (S) (v, h) are separated that at this point (B) from the commissioning of the coordinate input device at (E) in this one pulse (e) for the forced switchover with every picture change is generated on self-image at the sending subscriber A that the synchronization signals (v, h), the self-image switching impulses (e) and those from the coordinate input device (E) determined coordinates of the visible character (P) corresponding pulses (d) added in a mixing stage (M2) and to the sending point (A) via the associated Image channel (b) are transmitted that the Eigenbildumschalteimpuls (e) in addition for switching (4) to self-image at the sending point (A) from a detector (U) is determined and causes the time interval (f) of the received of the transmitted synchronization signals (v, h) with the aid of at least one counter (Zt, Z2) and at least one clock generator (T1, T2) incrementing this counter to be measured, whereupon the counter (Z1, Z2) is stopped and waits for a coordinate pulse (d) switches it on again, that in the event of failure of the coordinate pulse (d) the counter (Z1, Z2) is reset with the next synchronization pulse (v, h) and starts counting again that if a coordinate pulse (d) the counter tZ1, Z2) has switched on, this continues to count until a specified, the technical Data (image standard) of the television telephone system corresponding number is reached, and that when this number is reached, the visible character (P) in the image signal to be transmitted appears. 2. The method according to claim 1, d a d u r c h g e k e n n -z e i c h n e t that when using two counters (Zl, Z2) and two clock generators (Tl, T2) to advance this counter, the one counter (Zi) the distance between the vertical sync signals (v) according to the contained lines (35), the other counter (z2) but the distance of the horizontal sync signals (h) corresponding to the number of pixels in the Line measures to determine the coordinates of the visible character (r) that the Clock sequence of the act generators (T1, T2) according to the required accuracy is measured, and that if the end numbers of the two counters coincide, an AND gate (G) the visible sign (P) to be faded in to a mixer amplifier (M1) in the self-image the sending point (A) can pass through.